Production system for producing hydrocarbons from a well

ABSTRACT

The present invention relates to a production system ( 1 ) for producing hydrocarbons from a well ( 2 ). Said production system comprises a production casing ( 3 ), a monitoring unit adapted to measure a production outcome of the well, a first reservoir zone ( 6 ) comprising at least a first fluid ( 10 ), extending along and outside part of the production casing, a second reservoir zone ( 7 ) comprising at least a second fluid ( 11 ), extending along and outside another part of the production casing, a first inflow device arranged in the first reservoir zone having a first inflow area and being adapted to let the first fluid into the production casing at a first volume rate (VI), a second inflow device arranged in the second reservoir zone having a second inflow area and being adapted to let the second fluid into the production casing at a second volume rate (V 2 ), wherein the first and second inflow areas of the inflow devices are adjustable, whereby the first and second inflow devices can be adjusted so that the first volume rate is equal to or higher than the second volume rate. Furthermore, the present invention relates to a well completion comprising the production system according to the invention as well as to a production method for the production of hydrocarbons from a well.

FIELD OF THE INVENTION

The present invention relates to a production system for producinghydrocarbons from a well. Furthermore, the present invention relates toa well completion comprising the production system according to theinvention as well as to a production method for the production ofhydrocarbons from a well.

BACKGROUND ART

During oil and gas production, it is sometimes necessary to assist theproduction in a well due to a high hydro-static pressure. If the wellitself is not capable of generating the adequate pressure to drive oilor gas to the surface, or the well has been deliberately killed,artificial lift may be used to lift the well fluid at the upper part ofthe well.

By submerging a pump into a well, the pump may be used to boost thepressure or perhaps restart a dead well. The pump sets a plug or seal inthe well and pumps well fluid from one side of the plug to the other toovercome the static pressure of the well fluid above the pump.

Other methods of artificial lifting use chemicals or gasses to providethe lift required to ensure an acceptable production outcome from thewell. However, the known solutions overcoming the static pressure of thewell fluid use external energy sources.

SUMMARY OF THE INVENTION

It is an object of the present invention to wholly or partly overcomethe above disadvantages and drawbacks of the prior art. Morespecifically, it is an object to provide an improved production systemfor producing hydrocarbons from a well without using an artificial liftsystem, such as a pump, gas or chemicals.

The above objects, together with numerous other objects, advantages, andfeatures, which will become evident from the below description, areaccomplished by a solution in accordance with the present invention by aproduction system for producing hydrocarbons from a well, comprising

-   -   a production casing,    -   a monitoring unit adapted to measure a production outcome of the        well,    -   a first reservoir zone comprising at least a first fluid,        extending along and outside part of the production casing,    -   a second reservoir zone comprising at least a second fluid,        extending along and outside another part of the production        casing,    -   a first inflow device arranged in the first reservoir zone,        having a first inflow area and being adapted to let the first        fluid into the production casing at a first volume rate, and    -   a second inflow device arranged in the second reservoir zone,        having a second inflow area and being adapted to let the second        fluid into the production casing at a second volume rate,        wherein the first and second inflow areas of the inflow devices        are adjustable, whereby the first and second inflow devices can        be adjusted so that the first volume rate is equal to or higher        than the second volume rate.

Hereby, a production system is obtained wherein the energy in thereservoir and well is used for lifting the well fluid out of the well,substantially without using external energy sources.

In an embodiment, the inflow device comprises a first outer sleeve and asecond inner sleeve movable in relation to each other, the first outersleeve having outer inflow openings arranged in rows with a differentnumber of openings in each row, and the second inner sleeve having inneropenings, whereby the inflow area of the inflow device is adjustable inthat the inner openings of the second inner sleeve can be moved andaligned in relation to the outer openings of the first sleeve.

Said inflow openings may be arranged in rows along the inflow device.

Furthermore, the inner openings may be arranged with a distance betweenthem in relation to the outer openings, whereby the inflow area of theinflow device is adjustable in that the inner openings of the secondinner sleeve can be moved and aligned in relation to the outer openingsof the first sleeve.

Moreover, the inner openings of the inner sleeve may be arranged withpredetermined circumferenctial distances between them so that each rowof outer inflow openings can optionally be opened or closed by movingthe inner sleeve.

In one embodiment, the second inner sleeve may be rotatably movable inrelation to the first outer sleeve.

In another embodiment, the inflow device may have an axial extension,and the inner sleeve may be slidable in relation to the outer sleevealong the axial extension.

Furthermore, the outer sleeve may have a recess in which the innersleeve slides along the axial extension.

In yet another embodiment, the second sleeve may comprise recesses forengaging with a key tool for adjusting the inflow device.

In yet another embodiment, the inner sleeve may be slidably movable inrelation to the outer sleeve.

In addition, the production system as described above may furthercomprise a monitoring unit adapted to measure a production outcome ofthe well.

Moreover, the monitoring unit may be adapted to measure a water contentof the production outcome so that the inflow devices may be adjusted toobtain an optimum between production outcome and water content.

Also, the monitoring unit may be adapted to measure a volume rate of theproduction outcome and/or a pressure at the top of the well so that theinflow devices may be adjusted based on the volume rate and/or pressuremeasured at the top of the well.

In one embodiment, the inflow devices may be manually adjustable.

In another embodiment, the inflow devices may be remotely adjustable.

Furthermore, the inflow device may be operated by a magnetic source.

Moreover, the reservoir zones may be separated by annular barriers.

In an embodiment, the system may comprise a plurality of reservoirzones.

Further, a plurality of inflow devices may be arranged in the systemand/or in each reservoir zone.

Said plurality of inflow devices may be arranged in the system and/or ineach reservoir zone.

Also, the first fluid may be oil and the second fluid may be water orgas.

In addition, a valve may be arranged in one or more of the openings.

Furthermore, a screen may be arranged outside the openings.

In one embodiment, the inflow device may comprise a first packer, thesecond sleeve may be arranged in a recess of the first sleeve, and thefirst packer may be arranged between the first sleeve and the secondsleeve.

Furthermore, the packer may extend around the inner circumferentialrecess and have an inner diameter which is substantially the same asthat of the second sleeve.

Moreover, the packer may have a number of through-going packer channelsfor being aligned with first axial channels in the first sleeve.

In addition, the packer may be made of ceramics.

In an embodiment, the production casing may comprise annular barriers,each annular barrier being adapted for being expanded in an annulusbetween the production casing and an inside wall of a borehole downhole,and each annular barrier comprising:

-   -   a tubular part for mounting as part of the production casing,    -   an expandable sleeve surrounding the tubular part, each end of        the expandable sleeve being fastened to the tubular part by        means of a connection part,    -   an annular barrier space between the tubular part and the        expandable sleeve, and    -   an aperture in the tubular part for letting fluid into the        annular barrier space to expand the sleeve,        wherein annular barriers are arranged, separating the first        reservoir zone and the second reservoir zone.

Furthermore, the expandable sleeve may be made of metal.

The present invention also relates to a well completion comprising theproduction system as described above and a well head.

The well completion may further comprise a control unit arranged in thewell head for adjusting the inflow devices.

In addition, the well completion may further comprise a key toolconnected with a downhole tractor for adjusting the inflow devices.

Further, the present invention relates to a production method forproduction of hydrocarbons from a well, comprising the steps of:

-   -   determining a first reservoir zone comprising at least a first        fluid,    -   determining a second reservoir zone comprising at least a second        fluid,    -   opening a first inflow device in the first zone to let the at        least first fluid into a production casing at a first volume        rate,    -   opening a second inflow device in the second zone to let the at        least second fluid into the production casing at a second volume        rate,    -   monitoring a production outcome of the well, and    -   adjusting the first and second inflow devices based on the        production outcome so that the first volume rate is equal to or        higher than the second volume rate or so that the second volume        rate is higher than the first volume rate.

In said method, the monitoring step may comprise one or more of thesteps of:

-   -   measuring a pressure at the top of the well,    -   measuring a volume rate of the production outcome at the top of        the well, and/or    -   measuring a water content of the production outcome at the top        of the well.

Also, the step of adjusting the first and second inflow devices mayfurther comprise adjustment of at least one of the inflow devices basedon the measured pressure, volume rate and/or water content at the top ofthe well.

Moreover, the step of step of adjusting the first and second inflowdevices may be performed manually, e.g. by a key tool connected with adownhole tractor.

Additionally, the step of adjusting the first and second inflow devicesfurther may be performed remotely from the top of the well.

Finally, the step of adjusting the first and second inflow devicesfurther may be performed wirelessly.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its many advantages will be described in more detailbelow with reference to the accompanying schematic drawings, which forthe purpose of illustration show some non-limiting embodiments and inwhich

FIG. 1 shows a production system according to one embodiment of theinvention,

FIG. 2 shows another embodiment of the production system having aplurality of reservoir zones,

FIG. 3 shows a diagram of volume rate in relation to pressure,

FIG. 4 shows a cross-sectional view of an embodiment of an inflowdevice,

FIG. 5 shows a cross-sectional view of another embodiment of an inflowdevice,

FIG. 6 shows a cross-sectional view of an additional embodiment of aninflow device,

FIG. 7 shows, in a partly cross-sectional view and partly inperspective, the inflow device of FIG. 4,

FIGS. 8 a-8 o show cross-sectional views of different positions of theinflow device of FIGS. 4 and 7 in relation to the volume rate,

FIG. 9 shows a cross-sectional view of the inflow device of FIG. 6,

FIG. 10 shows, in a partly cross-sectional view and partly inperspective, another embodiment of the inflow device having an axiallysliding inner sleeve, and

FIG. 11 shows a cross-sectional view of the inflow device of FIG. 10along the axial extension.

All the figures are highly schematic and not necessarily to scale, andthey show only those parts which are necessary in order to elucidate theinvention, other parts being omitted or merely suggested.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a production system 1 for producing hydrocarbons from awell 2. The production system 1 comprises a production casing 3extending along the well 2. The production system 1 furthermorecomprises a monitoring unit 4 adapted to measure a production outcome ofthe well 2. In this embodiment, the monitoring unit is positioned at thetop of the well 2, i.e. at the well head 5. The monitoring unit maycomprise a flow measuring device, a pressure sensor, a water cutmeasuring device or a combination thereof.

The production system 1 also comprises a first reservoir zone 6comprising at least a first fluid 10, extending along and outside theproduction casing 3, and a second reservoir zone 7 comprising at least asecond fluid 11, extending along and outside the production casing.Furthermore, a first inflow device 8 is arranged in the first reservoirzone 6, having a first inflow area and being adapted to let the firstfluid 10 into the production casing 3 at a first volume rate V1, and asecond inflow device 9 is arranged in the second reservoir zone 7,having a second inflow area and being adapted to let the second fluid 11into the production casing 3 at a second volume rate V2. The first andsecond inflow areas of the inflow devices 8, 9 are adjustable, wherebythe first and second inflow devices 8, 9 can be adjusted based on theproduction outcome so that the first volume rate V1 is equal to orhigher than the second volume rate V2.

Hereby, it is obtained that the production of hydrocarbons from the well2 may be optimised by adjusting the inflow volume rates of the inflowdevices 8, 9 to the instantaneous requirement based on either the volumerate of the production outcome, the pressure at the top of the well 2,the water content of the production outcome, or a combination thereof.Thus, by means of the present system, it is possible to create lift ofthe fluids in the well by adjusting the inflow volume rates of thefluids and thereby avoid using artificial lift or at least substantiallyreduce the use of artificial lift.

In the event that the first fluid 10 comprises more water or gas, it maybe used for driving the second and heavier fluid 11, and thus,artificial lift higher up the well may be avoided. Similarly, the secondfluid may have a higher content of water which is normally shut off byhindering its inflow into the casing, however, the second fluid may beuseful for mixing with the first fluid to ease the flow of the well ofthe first fluid.

In the production system 1 shown in FIG. 1, the first and secondreservoir zones 6, 7 are adjacent zones, and they are separated fromeach other by expandable annular barriers 12. In FIG. 1, the first fluid10 in the first reservoir zone 6 is essentially oil and the second fluid11 in the second reservoir zone 7 is essentially water. The first andsecond reservoir zones 6, 7 each has a reservoir pressure of 300 bar.The first inflow device 8 of the first reservoir zone 6 is adjusted tolet in the first fluid 10, i.e. oil, so that there is a pressure of 200bar in the production casing 3. Thereby, there is a pressure differenceof 100 bar between the reservoir and the casing. The second inflowdevice 9 of the second reservoir zone 7 is adjusted to let in the secondfluid 11, i.e. water, so that there is a pressure of 250 bar in theproduction casing 3, i.e. the 200 bar from the first zone and 50 barfrom the second zone. Thereby, a there is a pressure difference of 50bar between the reservoir at the second zone and the production casing.By letting in the second fluid 11, i.e. water, a higher water content isobtained in the production outcome. However, at the same time, a highervolume rate of the production outcome and enhanced lift to the well areachieved. In fact, the energy in the reservoir is utilised for liftingthe well instead of using secondary means, such as an artificial lift bymeans of gas, or adding chemicals, for providing lift.

In FIG. 2, the production system has five reservoir zones 6, 7, 13, 14,15 mutually separated by expandable annular barriers 12. In FIG. 2, thefirst and second reservoir zones 6, 7 are separated by another reservoirzone 14 having a third fluid 10 b with a lower oil content than thefirst fluid 10. Below the first zone 6 furthest away from the well head5, there is another reservoir zone 13 having a fourth fluid 10 a whichalso has a lower oil content than the first fluid 10. Furthermore, abovethe second zone 7, there is a fifth zone 15 having a fourth fluid 11 awith a lower water content than the second fluid 11. Furthermore, one ormore of the additional inflow devices 16, 17, 18 arranged in the otherreservoir zones 13, 14, 15, respectively, may also be adjusted to letfluid at certain volume rates into the production casing to enhance thelift in the well and provide an optimum production outcome. Thus, theproduction system 1 may function in the same manner as described inrelation to FIG. 1.

FIG. 3 shows a diagram disclosing different relationships between volumerate of the production outcome and pressure. As an example, the diagramhas three different curves 19, 20, 21 each representing varying volumerates at a certain pressure. In the example above disclosed in FIG. 1,the first inflow device is positioned at a high volume rate at apressure lower than that of the second inflow device, and the fluidthere-through would therefore follow curve 20. The second device ispositioned at a lower volume rate but at a higher pressure, and thefluid there-through will therefore be positioned on curve 21 but not ata volume rate as high as that of the fluid through the first inflowdevice. From the diagram, it is deducible that a high pressure and ahigh volume rate, cf. curve 21, provide a high production outcome.

FIG. 4 shows a cross-sectional view of the inflow device 8 along anaxial extension of the inflow device 8 being concentric with the axialextension of the casing. In this embodiment, the inflow device 8comprises an outer sleeve 22 and an inner sleeve 23, and the innersleeve 23 may be movable in relation to the outer sleeve 22. Thecross-sectional view is taken along a row of inflow openings 24 arrangedin the extension of the inflow device 8. In this row, there are seveninflow openings 24. The inflow area of the inflow device is inter aliaconstituted by these inflow openings 24 each having an opening area. Ifthe inflow device 8 has several rows of inflow openings, the totalopening area of all these rows provides the total available inflow areaof the inflow device. The inflow openings 24 are in fluid connectionwith the inner opening 25 of the second inner sleeve 23 so that fluidfrom the reservoir may flow in through the inflow device 8. In thisembodiment, the inner opening 25 is shown as a through-going grooveextending in the axial extension of the inflow device 8. The inneropening 25 has a larger extension than the inflow openings 24 to ensurethat the inner opening 25, when being aligned with the inflow openings,does not prevent the fluid from flowing. A screen 26 or filter isarranged on the outside of the inflow openings.

Another embodiment of the inflow device 8 is shown in FIG. 5 in across-sectional view along an axial extension of the inflow device 8.The inflow device 8 also comprises the outer sleeve 22 and the innersleeve 23 which are movable in relation to each other. The inflowopenings 24 are in fluid connection with the inner openings 25 of thesecond inner sleeve 23 to allow fluid from the reservoir to flow inthrough the inflow device 8. In this embodiment, the inner openings 25are shown as seven through-going holes being aligned with the inflowopenings 24 of the outer sleeve. The inner openings 25 have a largerextension than each of the inflow openings 24 so they do not prevent thefluid from flowing. Again, a screen 26 or filter is arranged on theoutside of the inflow openings 24.

An additional embodiment of the inflow device 8 is shown in FIG. 6 in across-sectional view along a row of inflow openings 24 arranged in theextension of the inflow device 8. The inflow openings 24 terminate in anaxially extending channel 27 arranged in the wall of the outer sleeve22. The axial channel 27 abuts an axial channel 55 arranged in the innersleeve 23, whereby the inflow openings 24 are in fluid communicationwith the inner opening 25 via the two axial channels 27, 55,respectively. Also, in this embodiment, a screen 26 or filter isarranged on the outside of the inflow openings 24. The embodiment of theinflow device 8 shown in FIG. 6 will be described further in connectionwith FIG. 9 below.

The inflow device 8 of FIG. 4 is shown in perspective in FIG. 7. Theinflow device 8 comprises the outer sleeve 22 and the inner sleeve 23,wherein the inner sleeve 23 is movable in relation to the outer sleeve22 by rotation. Four rows of inflow openings 24, 28, 29, 30 are arrangedadjacent to each other and along the axial extension of the inflowdevice 8. The first row has seven inflow openings 24, as shown in thecross-sectional view in FIG. 4. The second row has six inflow openings28. The third row has four inflow openings 29, and the fourth row hastwo inflow openings 30. The inflow openings 24, 28, 29, 30 of the fourrows constitute the inflow area of the inflow device 8.

In other embodiments, the inflow device may have a different number ofrows and a different number of inflow openings in each row. Thus, theembodiment shown in FIG. 7 is one configuration of the inflow device 8.

The inner sleeve 23 is shown in FIG. 7 with four inner openings 25visible in cross-section, and the openings 25 are each aligned with aninflow opening in the row of inflow openings 24 arranged in the outersleeve 22. Also, the inflow device 8 may have a different number ofinner openings and different positions along the periphery of the innersleeve.

FIGS. 8 a to 8 o show a sequence of different adjustments to differentpositions of the inflow device in relation to the desired inflow volumerate of the inflow device 8.

In the same manner as described above, the inflow device 8 comprises aninner sleeve 23 or tubular which is rotatable within the outer sleeve 22or tubular. The inflow device 8 is shown in a cross-sectional view of aradial extension of the inflow device 8. The outer sleeve 22 has fourrows of inflow openings, 24, 28, 29, 30. In the first row 24, there areseven inflow openings, as shown in FIG. 7, in the second row 28, thereare six openings, in the third row 29, there are four openings, and inthe fourth row, there are two openings. In FIG. 8 a, the inner sleeve 23has ten inner openings 25, 31, 32, 33, 34, 35, 36, 37, 38, 39 in theform of grooves, the grooves are shown in FIG. 4, and the openings arearranged along the periphery of the inner sleeve 23. The inner openings25, 31, 32, 33, 34, 35, 36, 37, 38, 39 are arranged with predetermineddistances between them so that each row of outer inflow openings 24 canoptionally be opened or closed by rotating the inner sleeve 23, whichwill be further described below.

In FIG. 8 a, the rows of inflow openings 24, 28, 29, 30 are all alignedwith the inner openings 31, 32, 33, 34 of the inner sleeve 23. Thus, inFIG. 8 a, all inflow openings 24, 28, 29, 30 of the inflow device 8 areopen, whereby fluid may flow through all nineteen openings. This is themaximum flow capacity of the inflow device 8.

In FIG. 8 b, the inner sleeve 23 is rotated slightly to the right,whereby the inner opening 25 is aligned with the first row of inflowopenings 24, the inner opening 31 is aligned with the row of inflowopenings 29, and the inner opening 32 is aligned with the row of inflowopenings 30. Thus, by this adjustment of the inflow device 8, the rowsof inflow openings 24, 29, 30 are open and the row of inflow openings 28is closed, resulting in thirteen openings being open. By rotating theinner sleeve even further so that the inner opening 25 is aligned withthe third row of inflow openings 29, four openings are open, and byrotating the inner sleeve even further so that the inner opening 25 isaligned with the fourth row of inflow openings 30, two openings areopen.

In FIG. 8 c, the inner sleeve 23 is rotated slightly to the left,whereby the inner opening 31 is aligned with the row of inflow openings28, the inner opening 32 is aligned with the row of inflow openings 29,and the inner opening 33 is aligned with the row of inflow openings 30.Thus, by this adjustment of the inflow device 8, the rows of inflowopenings 28, 29, 30 are open and the row of inflow openings 24 isclosed, resulting in twelve openings being open.

In FIG. 8 d, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 c, whereby the inner opening 32 isaligned with the row of inflow openings 24, the inner opening 33 isaligned with the row of inflow openings 28, and the inner opening 34 isaligned with the row of inflow openings 29. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 24, 28, 29 are open andthe row of inflow openings 30 is closed, resulting in seventeen openingsbeing open.

In FIG. 8 e, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 d, whereby the inner opening 33 isaligned with the row of inflow openings 24, the inner opening 34 isaligned with the row of inflow openings 28, and the inner opening 35 isaligned with the row of inflow openings 30. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 24, 28, 30 are open andthe row of inflow openings 29 is closed, resulting in fifteen openingsbeing open.

In FIG. 8 f, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 e, whereby the inner opening 34 isaligned with the row of inflow openings 24 and the inner opening 35 isaligned with the row of inflow openings 29. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 24, 29 are open and therows of inflow openings 28, 30 are closed, resulting in eleven openingsbeing open.

In FIG. 8 g, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 f, whereby the inner opening 35 isaligned with the row of inflow openings 28. Thus, by this adjustment ofthe inflow device 8, the row of inflow openings 28 are open and the rowsof inflow openings 24, 29, 30 are closed, resulting in six openingsbeing open.

In FIG. 8 h, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 g, whereby the inner opening 35 isaligned with the row of inflow openings 24 and the inner opening 36 isaligned with the row of inflow openings 30. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 24, 30 are open and therows of inflow openings 28, 29 are closed, resulting in nine openingsbeing open.

In FIG. 8 i, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 h, whereby the inner opening 36 isaligned with the row of inflow openings 28 and the inner opening 37 isaligned with the row of inflow openings 30. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 28, 30 are open and therows of inflow openings 24, 29 are closed, resulting in eight openingsbeing open.

In FIG. 8 j, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 i, whereby the inner opening 36 isaligned with the row of inflow openings 24 and the inner opening 37 isaligned with the row of inflow openings 29. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 24, 29 are open and therows of inflow openings 28, 30 are closed, and this adjustment thusresults in the same position as in FIG. 8 f.

In FIG. 8 k, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 j, whereby the inner opening 38 isaligned with the row of inflow openings 29 and the inner opening 39 isaligned with the row of inflow openings 30. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 29, 30 are open and therows of inflow openings 24, 28 are closed, resulting in six openingsbeing open.

In FIG. 8 l, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 k, whereby the inner opening 38 isaligned with the row of inflow openings 28 and the inner opening 39 isaligned with the row of inflow openings 29. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 28, 29 are open and therows of inflow openings 24, 30 are closed, resulting in ten openingsbeing open.

In FIG. 8 m, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 l, whereby the inner opening 38 isaligned with the row of inflow openings 24 and the inner opening 39 isaligned with the row of inflow openings 28. Thus, in this adjustment ofthe inflow device 8, the rows of inflow openings 24, 28 are open and therows of inflow openings 29, 30 are closed, resulting in thirteenopenings being open.

In FIG. 8 n, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 m, whereby the inner opening 39 isaligned with the row of inflow openings 24. Thus, by this adjustment ofthe inflow device 8, the rows of inflow openings 24 are open and therows of inflow openings 28, 29, 30 are closed, resulting in sevenopenings being open.

In FIG. 8 o, the inner sleeve 23 is rotated slightly to the left inrelation to the adjustment of FIG. 8 n, whereby all rows of inflowopenings 24, 28, 29, 30 are closed. Thus, by this adjustment, the inflowdevice 8 is closed.

The sequence of adjustments shown in FIGS. 8 a-8 o shows different flowcapacities of the inflow device 8, resulting in fourteen differentvolume rates. Even though some possible adjustments of the inflow device8 are not shown in FIGS. 8 a-8 o, it is evident for the skilled personthat the configuration of the inflow device 8 makes it possible to openand close all rows of inflow openings independently of each other byrotating the inner sleeve into the intended position.

FIG. 9 shows a longitudinal cross-sectional view of another embodimentof an inflow device 8. The inflow device 8 comprises a first sleeve ortubular 40 having twelve inflow openings 24 in a first wall 41 andtwelve first axial channels 27 extending in the first wall 41 from theinflow openings 24 to an outlet 53. By axial channels is meant that thechannels extend in an axial direction in relation to the inflow device8.

The inflow device also comprises a second sleeve 42 or tubular having afirst end 43 near the outlet 53 and a second end 44 and, in this view,six inner openings 25. Even though the second sleeve 42 or tubular onlyshows six inner openings 25, the number of inner openings is actuallythe same as in the first sleeve 40 or tubular, i.e. 12 inner openings.

Furthermore, the second sleeve 42 or tubular is rotatable within thefirst sleeve 40 or tubular, and the second sleeve 42 has a second wall45 having twelve second axial channels (not shown) extending in thesecond wall 45 from the first end 43 to the inner opening 25. Thus, eachinner opening 25 has its own second axial channel.

The second sleeve 42 or tubular is arranged in an inner circumferentialrecess 46 in the first wall 41 of the first sleeve 40 or tubular,meaning that when the second sleeve 42 or tubular is arranged in therecess, the second sleeve 42 or tubular will not decrease the overallinner diameter of the inflow device and thereby of the productioncasing.

The second sleeve 42 or tubular is rotatable in relation to the firstsleeve 40 or tubular at least between a first position, in which thefirst channel 27 and second channel (not shown) are aligned to allowfluid to flow from the reservoir into the production casing via thefirst end 43 of the second sleeve 42 or tubular, and a second position(the position shown in FIG. 9), in which the first channel 27 and secondchannel (not shown) are not aligned, meaning that fluid is preventedfrom flowing into the production casing.

The inflow device 8 also comprises a first packer 47 which is arrangedbetween the first sleeve 40 or tubular and the first end 43 of thesecond sleeve 42 or tubular. The packer 47 extends around the innercircumferential recess 46 and has an inner diameter which issubstantially the same as that of the second sleeve or tubular. Thepacker 47 has a number of through-going packer channels 48 correspondingto the number of first axial channels, i.e. in this embodiment twelve,the packer channels 48 being aligned with the first axial channels 27.The packer is fixedly connected with the first sleeve or tubular so thatthe packer channels 48 are fluidly connected with first axial channels.The packer is ring-shaped, and the through-going packer channels 48extend through the packer along the axial extension of the first sleeveor tubular.

The packer 47 is preferably made of ceramics, whereby it is possible tomake the contact surfaces of the packer 47 smooth, which enhances thesealing properties of the packer 47, since the smooth contact surfacemay be pressed closer to the opposite surface which is the first end 43of the second sleeve 42 or tubular. However, in other embodiments, thepacker may be made of metal, composites, polymers or the like.

Furthermore, a second packer 49 is arranged between the first sleeve 40or tubular and the second end 44 of the second sleeve 42 or tubular.However, in another embodiment, the second packer is omitted, wherebythe second end 44 of the second sleeve 42 or tubular faces the firstwall of the first sleeve 40 or tubular.

In FIG. 9, a first spring element 50 is arranged between the firstpacker 47 and the first sleeve 40 or tubular. The spring element 50 thusforces the first packer against the second sleeve 42 to provide a sealtherebetween.

Furthermore, the second sleeve 42 or tubular may comprise at least onerecess 51 accessible from within, the recess 51 being adapted to receivea key tool (not shown) for rotating the second sleeve 42 or tubular inrelation to the first sleeve 40 or tubular.

The adjustment of the inflow devices 8, 9 may be performed manually,e.g. by inserting a downhole tool having a key tool into the productioncasing and moving the downhole tool to the inflow device which needs tobe adjusted. The inflow devices 8, 9 may also be operated by a magneticsource.

The inflow device 8 of FIG. 7 has an inner sleeve 23 rotating inrelation to an outer sleeve 22, and in FIG. 10, the inner sleeve 23slides axially in relation to the outer sleeve 22. The inner sleeve 23slides in a recess in the outer sleeve 22, as shown in FIG. 11 where theinner sleeve covers three of the four rows shown in FIG. 10, and thus,all the inflow openings 24 except two are covered. The first rowcomprises eight inflow openings 24, the second row comprises six inflowopenings 24, the third row comprises four inflow openings 24, and thefourth row comprises two inflow openings 24. By sliding the sleeve backand forth in the recess along the inner surface of the outer sleeve, thenumber of inflow openings 24 which the fluid may flow through may bevaried in the same manner as in the embodiment of the inflow device 8shown in FIG. 7. In other embodiments of an inflow device having anaxially slidable inner sleeve, the inflow device may have a differentnumber of rows and a different number of inflow openings in each row.Thus, the embodiment shown in FIGS. 9 and 10 is only one configurationof the inflow device 8.

FIG. 1 shows the production casing comprising annular barriers, eachannular barrier being adapted for expansion in an annulus 52 between aproduction casing and an inside wall 54 of a borehole 55 downhole. Eachannular barrier comprises a tubular part 57 for mounting as part of theproduction casing and an expandable sleeve 58 surrounding the tubularpart. Each end 59, 60 of the expandable sleeve is fastened to thetubular part by means of a connection part 72. At least one end isslidably connected with the tubular part. The expandable sleevesurrounds the tubular part and defines an annular barrier space 73between the tubular part and the expandable sleeve. The annular barrierfurther comprises an aperture 71 in the tubular part for letting fluidinto the annular barrier space to expand the sleeve. The annularbarriers are arranged separating the first reservoir zone 6 and thesecond reservoir zone 7 so that three annular barriers provide tworeservoir zones. The expandable sleeve, the tubular part and theconnection parts are made of metal.

In other embodiments, the inflow devices may be remotely adjustable,e.g. by wireline or wireless control.

The inflow device 8 is adapted to be inserted and form part of theproduction casing 3, thus forming a cased completion (not shown).Accordingly, the ends of the inflow device 8 are adapted to be connectedwith another casing element by conventional connection means, forinstance by means of a threaded connection.

In the embodiments described above, the outer openings are shown asopenings per se. However, the outer openings may comprise flowrestrictors, throttles or valves, such as inflow control valves (notshown).

Even though the above-mentioned embodiments have been describedprimarily in relation to rotatable movement of the inner sleeve inrelation to the outer sleeve, the inner sleeve may be slidably movablein relation to the outer sleeve.

By fluid or well fluid is meant any kind of fluid that may be present inoil or gas wells downhole, such as natural gas, oil, oil mud, crude oil,water, etc. By gas is meant any kind of gas composition present in awell, completion, or open hole, and by oil is meant any kind of oilcomposition, such as crude oil, an oil-containing fluid, etc. Gas, oil,and water fluids may thus all comprise other elements or substances thangas, oil, and/or water, respectively.

By a casing is meant any kind of pipe, tubing, tubular, liner, stringetc. used downhole in relation to oil or natural gas production.

In the event that the tools are not submergible all the way into thecasing, a downhole tractor can be used to push the tools all the wayinto position in the well. A downhole tractor is any kind of drivingtool capable of pushing or pulling tools in a well downhole, such as aWell Tractor®.

Although the invention has been described in the above in connectionwith preferred embodiments of the invention, it will be evident for aperson skilled in the art that several modifications are conceivablewithout departing from the invention as defined by the following claims.

1-22. (canceled)
 23. A production system for producing hydrocarbons froma well, comprising: a production casing, a first reservoir zonecomprising at least a first fluid, extending along and outside a part ofthe production casing, a second reservoir zone comprising at least asecond fluid, extending along and outside another part of the productioncasing, a first inflow device arranged in the first reservoir zone,having a first inflow area and being adapted to let the first fluid intothe production casing at a first volume rate, and a second inflow devicearranged in the second reservoir zone, having a second inflow area andbeing adapted to let the second fluid into the production casing at asecond volume rate, wherein the first and second inflow areas of theinflow devices are adjustable, whereby the first and second inflowdevices can be adjusted so that the first volume rate is equal to orhigher than the second volume rate, wherein the inflow device comprisesa first outer sleeve and a second inner sleeve movable in relation toeach other, characterised in that the first outer sleeve having outerinflow openings arranged in rows with a different number of openings ineach row, and the second inner sleeve having inner openings, whereby theinflow area of the inflow device is adjustable in that the inneropenings of the second inner sleeve can be moved and aligned in relationto the outer openings of the first sleeve.
 24. A production systemaccording to claim 23, wherein the inner openings are arranged with adistance between them which is different from a distance between theouter openings, whereby inflow area of the inflow device is adjustablein that the inner openings of the second inner sleeve can be moved andaligned in relation to the outer openings of the first sleeve.
 25. Aproduction system according to claim 23, wherein the inner openings ofthe inner sleeve may be arranged with predetermined circumferenctialdistances between them so that each row of outer inflow openings canoptionally be opened or closed by moving the inner sleeve.
 26. Aproduction system according to claim 23, further comprising a monitoringunit adapted to measure a production outcome of the well.
 27. Aproduction system according to claim 26, wherein the monitoring unit isadapted to measure a water content of the production outcome so that theinflow devices may be adjusted to obtain an optimum between productionoutcome and water content.
 28. A production system according to claim26, wherein the monitoring unit is adapted to measure a volume rate ofthe production outcome and/or a pressure at the top of the well so thatthe inflow devices may be adjusted based on of the volume rate and/orpressure measured at the top of the well.
 29. A production systemaccording to claim 23, wherein the reservoir zones are separated byannular barriers.
 30. A production system according to claim 23, whereinthe first fluid is oil and the second fluid is water or gas.
 31. Aproduction system according to claim 23, wherein the inflow devicecomprises a first packer, the second sleeve is arranged in a recess ofthe first sleeve, and the first packer is arranged between the firstsleeve and the second sleeve.
 32. A production system according to claim31, wherein the packer extends around the inner circumferential recessand has an inner diameter which is substantially the same as that of thesecond sleeve.
 33. A production system according to claim 31, whereinthe packer has a number of through-going packer channels for beingaligned with first axial channels in the first sleeve.
 34. A productionsystem according to claim 31, wherein the packer is made of ceramics.35. A production system according to claim 23, wherein the productioncasing comprises annular barriers, each annular barrier being adaptedfor being expanded in an annulus between the production casing and aninside wall of a borehole downhole, and each annular barrier comprising:a tubular part for mounting as part of the production casing, anexpandable sleeve surrounding the tubular part, each end of theexpandable sleeve being fastened to the tubular part by means of aconnection part, an annular barrier space between the tubular part andthe expandable sleeve, and an aperture in the tubular part for lettingfluid into the annular barrier space to expand the sleeve, whereinannular barriers are arranged, separating the first reservoir zone andthe second reservoir zone.
 36. A production system according to claim35, wherein the expandable sleeve is made of metal.
 37. A wellcompletion comprising the production system according to claim 23 and awell head.
 38. A well completion according to claim 37, furthercomprising a control unit arranged in the well head for adjusting theinflow devices.
 39. A production method for production of hydrocarbonsfrom a well by means of the production system according to claim 23,comprising the steps of: identifying a first reservoir zone comprisingat least a first fluid, identifying a second reservoir zone comprisingat least a second fluid, opening a first inflow device in the first zoneto let the at least first fluid into a production casing at a firstvolume rate, opening a second inflow device in the second zone to letthe at least second fluid into the production casing at a second volumerate, monitoring a production outcome of the well, and adjusting thefirst and second inflow devices based on the production outcome so thatthe first volume rate is equal to or higher than the second volume rateor so that the second volume rate is higher than the first volume rate.40. A method according to claim 39, wherein the monitoring stepcomprises one or more of the steps of: measuring a pressure at the topof the well, measuring a volume rate of the production outcome at thetop of the well, and/or measuring a water content of the productionoutcome at the top of the well.
 41. A method according to claim 39,wherein the step of adjusting the first and second inflow devicesfurther comprises adjustment of at least one of the inflow devices basedon the measured pressure, volume rate and/or water content at the top ofthe well.
 42. A method according to claim 39, wherein the step ofadjusting the first and second inflow devices is performed manually,e.g. by a key tool connected with a downhole tractor.